A conventional LED package structure often includes a white insulating substrate, a transparent or white die-attach adhesive, and a transparent encapsulant for improving brightness thereof. However, when the conventional LED package structure is used as a light source in an indoor display device, glare phenomenon may happen under a relatively low ambient lighting condition. This glare phenomenon is attributed to the transparent or white die-attach adhesive. The glare phenomenon not only reduces contrast ratio of the display device but also makes the eyes of a user feel uncomfortable.
Therefore, when an LED package structure is used as a light source in an indoor display device, it is important to consider how to improve contrast ratio of the display device and comfort for the eyes of a user.